1. Field of Invention
This invention relates to an optical connector used with a multiplex transmission circuit of a vehicle, such as an automobile, a sleeve placed in a receptacle forming a part of the optical connector, and a manufacturing method for the sleeve.
2. Related Art
As this type of optical connector and sleeve, an optical connector previously proposed by the applicant (art disclosed in JP-B-6-33443UM) is generally known.
The optical connector and sleeve disclosed in the gazette will be discussed with reference to FIGS. 9 to 11.
First, in FIG. 9, reference numeral 1 denotes an optical connector and the optical connector 1 comprises a receptacle 2 as a machine side connector and an optical plug 3 as an optical fiber side connector.
As shown in FIGS. 9 and 10, the receptacle 2 has a housing 4 made of a synthetic resin and storage chambers 5 and 5 in the housing 4 stores reception and transmission modules 6 and 6xe2x80x2 in a state in which they are supported on back sheets 7 and 7 each made of an elastic member such as rubber. On the rear face, a cap 8 is placed, and reception tubes 10 and 10 extended forward matching the axes of lenses 9 and 9 are placed ahead of the storage chambers 5 and 5 in which the reception and transmission modules 6 and 6xe2x80x2 are supported. Sleeves 13 and 13 each comprising a light transmission member 11 consisting of a core and a clad (not shown) (for example, a multimode plastic optical fiber of about Ø1) bonded and fixed to a holder 12 like a metal cylinder and ground on both end faces are inserted into the reception tubes 10 and 10.
The optical fiber 3 is fitted and connected to the receptacle 2 and as shown in FIGS. 9 and 11, comprises ferrule assemblies 15 and 15 for covering optical fibers 14 and 14 (only one is shown throughout the drawings) in a state in which the ends of the optical fibers 14 and 14 are exposed at the tips, a plug housing 17 provided with a tubular partition wall 16 for housing and protecting the ferrule assemblies 15 and 15, a spring cap 18 fitted and fixed to the plug housing 17, and a boot 19 fitted to the rear part of the spring cap 18.
The plug housing 17 is formed with shoulder part 17a engaging collar-like retention parts 15a and 15a placed in the latter half parts of the outer peripheries of the ferrule assemblies 15 and 15 and springs 20 and 20 are placed between the retention parts 15a and 15a and inner tube parts 18a and 18a of the spring cap 18 so that the ferrule assemblies 15 and 15 are urged forward all the time.
The retention parts 15a and 15a engage the shoulder part 17a, whereby tip parts A of the ferrule assemblies 15 and 15 (see FIG. 11; corresponding to positions of incidence and emission end faces (light reception face and light emission face) of the optical fibers 14) are always retracted inside from front end face B of the plug housing 17 (see FIG. 11).
In the described configuration, connection of the receptacle 2 and the optical plug 3 will be discussed with reference to FIG. 9.
When the optical plug 3 is fitted to the receptacle 2, the reception tubes 10 and 10 enter the plug housing 17 and at the same time, the ferrule assemblies 15 and 15 enter the reception tubes 10 and 10.
The ferrule assemblies 15 and 15 abut the tips of the reception tubes 10 and 10 and adequate contact pressure is kept by the elastic force of the springs 20 and 20.
In this state, the tip parts A (see FIG. 11) and the sleeves 13 and 13 and the lenses 9 and 9 and the sleeves 13 and 13 are placed with gaps (not shown) kept to the minimum, whereby the gap loss of the optical connector 1 is minimized, so that a transmission margin when light communication is executed can be widened.
By the way, in the described related art, a gap of 6 mm, for example, on the structure exists between the reception and transmission module 6, 6xe2x80x2 and the optical fiber 14, 14, and the sleeve 13, 13 6 mm long, for example, is placed so as to bridge the gap. Preferably, the gap between the reception, transmission module 6, 6xe2x80x2 and the sleeve 13, 13 and the gap between the optical fiber 14, 14 and the sleeve 13, 13 is made zero from the relation of the described gap loss.
However, it is very difficult to make the gaps zero because of the combination of the members; in even the described optical connector 1, a slight gap occurs in some cases and a light power loss occurs.
Taking the gap between the transmission module 6xe2x80x2 and the sleeve 13 (not shown) as an example in the description, the transmission module 6xe2x80x2 usually uses a light emitting diode and therefore if a gap occurs, a part of light emitted and diverged (emitted like radiation) from the light emitting diode leaks through the gap. A part of the leakage light is not again incident on the light transmission member 11 of the sleeve 13, of course; thus the light leakage part leads to a light power loss.
Since a plastic optical fiber (POF) having the same N.A. (numerical aperture)=0.5 as the optical fiber 14 has been used as the light transmission member 11, there is a limit on reception of light from the transmission module 6xe2x80x2 (light emitting diode). Of course, larger light than the N.A. of the light transmission member 11 exists, thus a light power loss cannot be avoided if the above-mentioned gap is contained.
Letting the refractive index of the core be n1 and that of the clad be n2 (n1 greater than n2), the above-mentioned N.A. is defined by a relational expression of N.A.=[(n1)2xe2x88x92(n2)2]xc2xd.
On the other hand, the above-described light power loss is caused by not only the gap, but also by the assembly state (position) of the sleeve 13, 13.
That is, the receptacle 2 is made of a synthetic resin and a minute protrusion (not shown) for retaining the sleeve 13 is formed in the reception tube 10 molded integrally with the receptacle 2 and the sleeve 13 having the metal holder 12 is inserted into the reception tube 10. When the sleeve 13 is inserted, the minute protrusion is scraped, for example, by the holder 12 and a longitudinal or lateral shift occurs in the optical axis. Resultantly, a light power loss occurs.
Giving a more detailed description, the sleeve 13 is ground on both end faces, thus the possibility that the end face of the holder 12 may be an edge is high and when the sleeve 13 is inserted into the reception tube 10, it is hard to say that the minute protrusion functions normally.
For example, if four minute protrusions are formed at equal intervals in the reception tube 10 and the sleeve 13 is inserted in an insertion axis shift state, at least one of the minute protrusions is scraped by the end face of the holder 12 or is excessively compressed and crashed or broken.
Thus, it is easily understood that the inserted sleeve 13 loses stability, causing a shift to occur in the optical axis.
Therefore, also in this case, like the above-described gap problem, it is said that a light power loss cannot be avoided.
On the other hand, FIG. 12 graphs the optical axis shift (on horizontal axis, mm units) in a state in which the above-mentioned gap (gap amount, mm units) is contained and the light power loss (on vertical axis, dB units) to relate them to each other.
As also seen in the figure, it is said that the gap and the optical axis shift largely cause the light power to be lost. It is preferred that the gap amount and the optical axis shift are extremely small and how to manage them becomes a point for decreasing the light power loss. If the light power loss can be decreased, it is made possible to widen a margin optically downstream from the optical connector 1.
By the way, the sleeve 13 is manufactured through a large number of steps, thus it is preferred that cost reduction is accomplished while the above-mentioned problems are solved. It is also preferred to deal with the yield produced in the manufacturing process of the optical fibers 14, namely, waste pieces (not shown) left after several optical fibers 14 are cut away from the optical fiber source line wound around a bobbin together with the above-mentioned problems.
If the gap is managed more strictly than formerly, it is feared that the productivity of the members and the optical connector 1 will lower because of the dimension accuracy of the members; it does not become a preferred measure.
It is therefore an object of the invention to provide an optical connector, a sleeve, and a manufacturing method for the sleeve for making it possible to decrease a light power loss, to widen a transmission margin when light communication is executed, and also to reduce costs.
To the end, according to a first aspect of the present invention, there is provided an optical connector comprising sleeves capable of providing optical connection of an optical fiber and reception and transmission modules, the sleeves being placed between the optical fiber and the reception and transmission modules, provided in that
N.A. of each of the sleeves is made larger than N.A. of the optical fiber.
In the optical connector of a second aspect of the present invention, in the optical connector as the first aspect of the present invention, the N.A. of at least the sleeve corresponding to the transmission module is made larger than the N.A. of the optical fiber.
In the optical connector of a third aspect of the present invention, in the optical connector of the first or the second aspect of the present invention, the N.A. of each of the sleeves is 0.5 less than N.A. less than 1.
In the optical connector of a fourth aspect of the present invention, in the optical connector of the first or the second aspect of the present invention, the N.A. of each of the sleeves is 0.6 or 0.7.
In the optical connector of a fifth aspect of the present invention, in the optical connector of the first to the fourth aspect of the present invention, the sleeve is made up of a light transmission member consisting of a core and a clad having a smaller refractive index than the core has and a cylindrical and coat-like holder placed in an outer peripheral margin of the light transmission member, the holder being formed of a synthetic resin material.
In the optical connector of a sixth aspect of the present invention, in the optical connector as the fifth aspect of the present invention, the holder is formed of a synthetic resin material which is a material equal to or softer than a member in which the sleeve is placed.
In the optical connector of a seventh aspect of the present invention, in the optical connector as the fifth or the sixth aspect of the present invention, the holder is formed of polyethylene.
In the optical connector of an eighth aspect of the present invention, in the optical connector as the fifth to seventh aspect of the present invention, the holder can be colored and is colored in a different color from that of the member in which the sleeve is placed.
In the optical connector of a ninth aspect of the present invention, in the optical connector as the eighth aspect of the present invention, the color of the holder is a different family color from the color of the member in which the sleeve is placed.
In the optical connector a tenth aspect of the present invention, in the optical connector as the eighth or ninth aspect of the present invention, the holder is colored in two distinguishable colors.
In the optical connector of an eleventh aspect of the present invention, in the optical connector as the tenth aspect of the present invention, one of the two distinguishable colors is orange if the color of the member in which the sleeve is placed is black.
In the optical connector of a twelfth aspect of the present invention, in the optical connector in any of the fifth to eleventh aspect, a collimator lens is formed at least at one end of the light transmission member.
In the optical connector of a thirteenth aspect of the present invention, in the optical connector in any of the first to twelfth aspect, the sleeve is formed by cutting an optical fiber source line or a waste tip of the optical fiber source line.
To the end, according to a fourteenth aspect of the present invention, there is provided a sleeve being placed between an optical fiber and a reception module or a transmission module placed in an optical connector and capable of providing optical connection of the optical fiber and the reception or transmission module, the sleeve comprising a light transmission member consisting of a core and a clad having a smaller refractive index than the core has and a cylindrical and coat-like holder placed in an outer peripheral margin of the light transmission member, provided in that the sleeve is formed in a larger N.A. than that of the optical fiber and is placed corresponding to at least the transmission module.
In the sleeve as a fifteenth aspect of the present invention, in the sleeve as claimed in claim 14, the larger N.A. than that of the optical fiber is 0.5 less than N.A. less than 1.
In the sleeve as a sixteenth aspect of the present invention, in the sleeve as the fourteenth aspect of the present invention, the larger N.A. than that of the optical fiber is 0.6 or 0.7.
In the sleeve as a seventeenth aspect of the present invention, in the sleeve as the fourteenth to the sixteenth aspect of the present invention, the holder is formed of a synthetic resin material which is a material equal to or softer than a receptacle forming a part of the optical connector.
In the sleeve of a eighteenth aspect of the present invention, in the sleeve as the seventeenth aspect of the present invention, the holder is formed of polyethylene.
In the sleeve of a nineteenth aspect of the present invention, in the sleeve as the seventeenth or the eighteenth aspect, the holder can be colored and is colored in a different color from that of the receptacle.
In the sleeve of a twentieth aspect of the present invention, in the sleeve as the nineteenth aspect of the present invention, the color of the holder is a different family color from the color of the receptacle.
In the sleeve of a twenty-first aspect of the present invention, in the sleeve as the nineteenth to the twentieth aspect of the present invention, the holder is colored in two distinguishable colors.
In the sleeve of a twenty-second aspect of the present invention, in the sleeve in any of the fourteenth to twenty-first aspect, a collimator lens is formed at least at one end of the light transmission member.
As the sleeve of a twenty-third aspect of the present, the sleeve in any of the fourteenth to the twenty-second aspect of the present invention, is formed by cutting an optical fiber source line or a waste tip of the optical fiber source line.
To the end, according to a twenty-fourth aspect of the present invention, there is provided a sleeve being placed between an optical fiber and a reception module or a transmission module placed in an optical connector and capable of providing optical connection of the optical fiber and the reception or transmission module, the sleeve comprising a light transmission member consisting of a core and a clad having a smaller refractive index than the core has and a cylindrical and coat-like holder placed in an outer peripheral margin of the light transmission member, provided in that the holder is formed of a synthetic resin material which is a material equal to or softer than a receptacle forming a part of the optical connector.
In the sleeve of a twenty-fifth aspect of the present invention, in the sleeve in the twenty-fourth aspect of the present invention, the holder can be colored and is colored in a different color from that of the receptacle.
In the sleeve of a twenty-sixth aspect of the present invention, in the sleeve in the twenty-fifth aspect of the present invention, the holder is colored in two distinguishable colors.
To the end, according to a twenty-seventh aspect of the present invention, there is provided a manufacturing method of a sleeve comprising a light transmission member consisting of a core and a clad having a smaller refractive index than the core has and a cylindrical and coat-like holder placed in an outer peripheral margin of the light transmission member, the manufacturing method comprising the steps of cutting an optical fiber source line or a waste tip of the optical fiber source line and then grinding both end faces.
In the manufacturing method of a twenty-eighth aspect of the present invention, in the manufacturing method in the twenty-seventh aspect of the present invention, the holder is colored before or after both end faces are ground.
According to the first aspect of the present invention, the N.A. of the sleeve is made larger, whereby the light reception amount of the sleeve, namely, the light reception limit becomes large and the coupling efficiency is improved. The transmission distance of the sleeve is markedly short as compared with that of the optical fiber, thus if the N.A. becomes large, the transmission speed is not affected and the transmission speed similar to that in the related art can be maintained. Further, the limit of light reception becomes markedly large as compared with that in the related art. Thus, if an optical axis shift occurs, the light power loss can be suppressed as much as possible.
Therefore, the optical connector intended for decreasing the light power loss and widening a transmission margin when light communication is executed can be provided.
According to the second aspect of the present invention, the N.A. of at least the sleeve corresponding to the transmission module is made large, whereby the reception limit of light emitted from the transmission module becomes markedly large than that in the related art.
Therefore, the optical connector intended for decreasing the light power loss and widening a transmission margin can be provided like that described above.
According to the third aspect of the present invention as claimed in claim 3, the N.A. of the sleeve can be selected matching the N.A. of the optical fiber used with the optical connector.
According to the fourth aspect of the present invention, the N.A. becomes more preferred N.A. considering the productivity and general versatility in the above-mentioned range. Advantages in the optical connector similar to those described above can be provided, of course.
According to fifth aspect of the present invention, it is made possible to protect the light transmission member by the holder as in the related art. The holder is a synthetic resin material and thus the holder itself becomes softer than the metal in the related art. When the holder is placed in the optical connector, the trouble as in the related art wherein the holding member of the sleeve is scraped on the end face of the holder is avoided. Thus, it is made possible to suppress an optical axis shift.
Therefore, the optical connector intended for decreasing the light power loss and widening a transmission margin can be provided like that described above.
According to the sixth aspect of the present invention, the holder is formed of a synthetic resin material which is a material equal to or softer than the member in which the sleeve is placed. Thus, it is made possible to suppress an optical axis shift.
Therefore, the optical connector intended for decreasing the light power loss and widening a transmission margin can be provided.
According to the seventh aspect of the present invention, a synthetic resin material having general versatility is used and it is made possible to contribute to cost reduction, of course.
Therefore, the optical connector that can also lead to cost reduction can be provided.
According to the eighth aspect of the present invention, the holder is colored, whereby whether or not the sleeve is reliably placed at a predetermined position can be checked easily, and widening a gap can be suppressed.
Therefore, the optical connector intended for decreasing the light power loss and widening a transmission margin can be provided.
According to the ninth aspect of the present invention, visibility is enhanced and it is made possible to determine the sleeve placement position reliably.
According to the tenth aspect of the present invention, the holder is colored in two distinguishable colors, so that visibility can be furthermore improved. It is made possible to determine the sleeve placement position reliably.
According to the eleventh aspect of the present invention, good visibility as a color combination is provided. Thus, it is hard to put a load on the worker who works for many hours; it is made possible to improve work efficiency.
Therefore, it can contribute to cost reduction.
According to the twelfth aspect of the present invention, if a collimator lens is provided on the incidence side, such light originally radiated to the clad can also be transmitted. In contrast, if a collimator lens is provided on the emission side, light can be gathered.
Therefore, the optical connector intended for decreasing the light power loss and widening a transmission margin can be provided like that described above.
According to the thirteenth aspect of the present invention, the sleeve is formed by cutting an optical fiber source line or a waste tip of the optical fiber source line and thus can be provided with general versatility. It contributes to improvement in yield and further the sleeve can be manufactured by recycling an optical fiber.
Therefore, the optical connector that can further lead to cost reduction can be provided.
According to the fourteenth aspect of the present invention, the reception amount of incident light, namely, the light reception limit becomes large and the coupling efficiency is improved. The transmission distance is markedly short as compared with that of the optical fiber, thus if the N.A. becomes large, the transmission speed involved in the whole of the optical fiber is not affected and the transmission speed similar to that in the related art can be maintained. Further, the limit of light reception becomes markedly large as compared with that in the related art. Thus, if an optical axis shift occurs, the light power loss can be suppressed as much as possible.
Therefore, the sleeve intended for decreasing the light power loss and widening a transmission margin when light communication is executed can be provided.
According to the fifteenth aspect of the invention, the N.A. of the sleeve can be selected matching the N.A. of the optical fiber placed in the optical connector.
According to the sixteenth aspect of the present invention, the N.A. becomes more preferred N.A. considering the productivity and general versatility in the above-mentioned range. Advantages in the sleeve similar to those described above can be provided, of course.
According to the seventeenth aspect of the present invention, the holder is formed of a synthetic resin material which is a material equal to or softer than the receptacle forming a part of the optical connector is placed. Thus, it is made possible to suppress an optical axis shift.
Therefore, the optical connector intended for decreasing the light power loss and widening a transmission margin can be provided.
According to the eighteenth aspect of the present invention, a synthetic resin material having general versatility is used and it is made possible to contribute to cost reduction, of course.
Therefore, the connector that can also lead to cost reduction can be provided.
According to the nineteenth aspect of the invention, the holder is colored, whereby whether or not the sleeve is reliably placed at a predetermined position can be checked easily, and widening a gap when the sleeve is placed in the optical connector can be suppressed.
Therefore, the sleeve intended for decreasing the light power loss and widening a transmission margin can be provided.
According to the twentieth aspect of the present invention as claimed in claim 20, when the sleeve is placed at the assembling time of the optical connector or the sleeve placement position is checked, visibility is enhanced. It is made possible for the worker to make an accurate determination as to placement of the sleeve.
According to the twenty-first aspect of the present invention, the holder is colored in two distinguishable colors, so that visibility can be furthermore improved. It is made possible to determine the sleeve placement position reliably.
According to the twenty-second aspect of the present invention, if a collimator lens is provided on the incidence side in the optical connector, such light originally radiated to the clad can also be transmitted. In contrast, if a collimator lens is provided on the emission side in the optical connector, light can be gathered.
Therefore, the sleeve intended for decreasing the light power loss and widening a transmission margin can be provided like that described above.
According to the twenty-third aspect of the present invention, the sleeve is formed by cutting an optical fiber source line or a waste tip of the optical fiber source line and thus the optical fiber can be provided with general versatility. It contributes to improvement in yield and further the sleeve can be manufactured by recycling an optical fiber.
Therefore, the sleeve that can further lead to cost reduction can be provided.
According to the twenty-fourth aspect of the present invention, it is made possible to protect the light transmission member by the holder as in the related art. The holder is a synthetic resin material and thus the holder itself becomes softer than the metal in the related art. When the holder is placed in the optical connector, the trouble as in the related art wherein the holding member of the sleeve is scraped on the end face of the holder is avoided. Thus, it is made possible to suppress an optical axis shift.
Therefore, the sleeve intended for decreasing the light power loss and widening a transmission margin can be provided.
According to the twenty-fifth aspect of the present invention, the holder is colored, whereby whether or not the sleeve is reliably placed at a predetermined position can be checked easily, and widening a gap when the sleeve is placed in the optical connector can be suppressed.
Therefore, the sleeve intended for decreasing the light power loss and widening a transmission margin can be provided.
According to the twenty-sixth aspect of the present invention as claimed in claim 26, the holder is colored in two distinguishable colors, so that visibility can be furthermore improved. It is made possible to determine the sleeve placement position reliably.
According to the twenty-seventh aspect of the present invention, such a manufacturing method is adopted, whereby the optical fiber placed in the optical connector can be provided with general versatility. It contributes to improvement in yield and further the sleeve can be manufactured by recycling an optical fiber.
Therefore, the sleeve manufacturing method that can lead to cost reduction can be provided.
According to the twenty-eighth aspect of the present invention, it is made possible to manufacture the sleeve independently of the coat color of the optical fiber source line that the holder is made of.
Therefore, it can further contribute to cost reduction.